The "variable pressure wand" option gives you the ability to perform a much wider range of cleaning jobs with the same machine. By attaching this ingenious tool to your wand assembly, you gain much greater control over water pressure. You may need to keep water from penetrating worn rubber seals or to clean without blasting water through doorframes. The increased flexibility also allows you to attach a variety of tools that will quickly clean carpets, upholstery,  awnings,  or wood,  then a minute later,  blast rust from steel...  Versatility Rocks!